Vicarious Visions is handling the PSP port of X-Men Legends II: Apocalypse, although from the few details we've heard about the game, it's much more than a typical port. Featuring additional branching storyline elements and a PSP-customized control set, this looks to be a more-than-perfect version of its bigger console brethren.
The screens we've seen so far look amazing, and Vicarious Visions is known for its solid reputation working with ports of some of Activision's biggest multiplatform hits (THPS titles, Spider-Man 2, and many more). The real question about the PSP version will be whether or not it supports infrastructure mode online multiplayer via WiFi. If it does, then PSP owners will likely flock to a solid four player online experience. If not, then the single-player mode had better be really great, because I have rarely met another PSP in public.
Of course, X-Men Legends is all about the multiplayer, and online play is a feature in the home console versions. Activision has been evasive regarding details of the PSP version's WiFi multiplayer support, only hinting that they have "something big" planned. Portable PlayStation gamers will just have to see for themselves in October, when X-Men Legends II: Rise of Apocalypse releases for PSP.